Systems and methods for detecting and measuring oxidizing compounds in test fluids

ABSTRACT

This disclosure relates to improved techniques for detecting and measuring oxidizing compounds in test fluids. Certain embodiments can include a measurement device that can be configured to apply a constant current to the test fluid and measure a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid. The measurement device also can be configured to measure a second voltage indicating an oxidizing potential of the test fluid, and to calculate an oxidizer concentration measurement indicating the concentration of the oxidizing compound in the test fluid based on a voltage difference between the reference voltage and the second voltage.

TECHNICAL FIELD

This disclosure is related to systems, methods, apparatuses, and techniques for detecting and measuring compounds in test fluids.

BACKGROUND

Oxidizing compounds (also referred to “oxidizing agents” or “oxidizers”) can be used to sanitize drinking water. In doing so, it is important to effectively measure the concentration of the oxidizing compounds to ensure both that a sufficient amount of the oxidizing compounds can be applied to sterilize the water, and that the water is safe for consumption.

Conventional apparatuses for making these measurements are plagued with various deficiencies. One deficiency is that the lifetime and reliability of these apparatuses are limited, thus requiring the measurement apparatuses to be replaced over relatively short periods of time. This deficiency can be attributed, at least in part, to the fact that these apparatuses typically rely on reference electrodes that rapidly lose chloride salts as a result of diffusion processes that take place while the reference electrodes are immersed in test fluids with the oxidizing compounds. This diffusion of salts from the reference electrodes reduces the lifetime of the reference electrodes, affects the reliability of the measurement apparatuses, and often causes failures of the measurement apparatuses.

BRIEF DESCRIPTION OF DRAWINGS

To facilitate further description of the embodiments, the following drawings are provided, in which like references are intended to refer to like or corresponding parts, and in which:

FIG. 1 is a block diagram of a system in accordance with certain embodiments;

FIG. 2 is a circuit diagram of a control board that may be utilized by a measurement device in accordance with certain embodiments;

FIG. 3 is a diagram illustrating how measurements are computed in accordance with certain embodiments;

FIG. 4 is a flow chart of an exemplary method in accordance with certain embodiments;

FIG. 5 is a flow chart of a second exemplary method in accordance with certain embodiments; and

FIG. 6 is a flow chart of a third exemplary method in accordance with certain embodiments.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present disclosure relates to improved systems, methods, apparatuses, and techniques for detecting and measuring oxidizing compounds in test fluids. In certain embodiments, a system comprises an improved measurement device that includes reference electrodes constructed of noble metals, passivated transition metals, and/or glassy carbons to prevent, or at least mitigate, oxidation of the reference electrodes, thus extending the lifetime of the measurement device and increasing the reliability of any measurements taken using the measurement device. In contrast to conventional measurement devices, the improved measurement device utilizes electrolysis to detect and measure oxidizing compounds in the test fluids. The measurement device can be utilized to make a variety of different measurements. In certain exemplary embodiments, the measurement device can use water electrolysis to measure oxidizing compounds (e.g., ozone) in water, such as drinking water and/or other types of water, using oxidation reduction potential (ORP) measurement techniques. In other exemplary embodiments, the probe can use electrolysis to take pH measurements, ion concentration measurements, potentiometric measurements, and/or other measurements.

In certain embodiments, a system is provided that comprises: (i) a test fluid comprising a concentration of an oxidizing compound; and (ii) a measurement device configured to: apply a constant current to the test fluid; measure a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid; measure a second voltage indicating an oxidizing potential of the test fluid; and calculate an oxidizer concentration measurement indicating the concentration of the oxidizing compound in the test fluid based on a voltage difference between the reference voltage and the second voltage.

In certain embodiments, a method is provided that comprises: applying a constant current to a test fluid comprising a concentration of an oxidizing compound; measuring, with a measurement device, a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid; measuring, with the measurement device, a second voltage indicating an oxidizing potential of the test fluid; and calculating, with the measurement device, an oxidizer concentration measurement indicating the concentration of the oxidizing compound in the test fluid based on a voltage difference between the reference voltage and the second voltage.

In certain embodiments, a system is provided that comprises: (i) a test fluid comprising a concentration of an oxidizing compound; and (ii) a measurement device comprising: (a) a processor; (b) a power supply that is configured to provide a constant current; and (c) a first electrode, a second electrode, and a third electrode, wherein: the first electrode and the second electrode are included on a circuit to which the constant current is applied when the first electrode and the second electrode are submerged in the test fluid, and the third electrode is not included on the circuit; the first electrode, the second electrode, and the third electrode are each comprised of a noble metal, a passivated transition metal, a glass-like carbon, or some combination thereof; the first electrode is configured to measure a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid; the third electrode is configured to measure a second voltage indicating an oxidizing potential of the test fluid; and the measurement device calculates an oxidizer concentration measurement indicating the concentration of the oxidizing compound in the test fluid based on a voltage difference between the reference voltage and the second voltage.

In certain embodiments, a system is provided that comprises: a test fluid; and a measurement device configured to: apply a constant current to the test fluid; measure a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid; measure a second voltage indicating a potential of the test fluid related to one of an oxidizing potential, a pH potential, or an ion concentration chemical potential; and calculate a concentration measurement in the test fluid based on a voltage difference between the reference voltage and the second voltage.

The embodiments described in this disclosure can be combined in various ways. Any aspect or feature that is described for one embodiment can be incorporated into any other embodiment mentioned in this disclosure. Moreover, any of the embodiments described herein may be hardware-based, may be software-based, or, preferably, may comprise a mixture of both hardware and software elements. Thus, while the description herein may describe certain embodiments, features, or components as being implemented in software or hardware, it should be recognized that any embodiment, feature, or component that is described in the present application may be implemented in hardware and/or software.

FIG. 1 is a block diagram of a system 100 in accordance with certain embodiments. The system 100 includes a measurement device 150, which includes electrodes 140 and a temperature measurement component 170 that are immersed in a test fluid 160. As an example, the test fluid 160 can be a liquid or a gas. The system 100 further includes a computing device(s) 110, a water management system 180, and an oxidizer generator 120. The computing device 110, the measurement device 150, the water management system 180, and the oxidizer generator 120 can be in indirect communication with each other over a network 130 and/or in direct communication with each other. The network 130 may represent any type of communication network, e.g., such as one that comprises a local area network (e.g., a Wi-Fi network), a personal area network (e.g., a Bluetooth network), a wide area network, an intranet, the Internet, a cellular network, and/or other types of networks. Although FIG. 1 may depict a single one of each of computing device 110, measurement device 150, water management system 180, and oxidizer generator 120, it should be understood this is not intended to be limiting, and the system can include any number of each component (e.g., computing devices 110, measurement devices 150, water management systems 180, and oxidizer generators 120) and sub-component (e.g., electrodes 140 and multiple temperature measurement components 170), and all of the components and sub-components can be configured to communicate with each other directly or indirectly.

All the components illustrated in FIG. 1, including the computing device 110, the measurement device 150, the water management system 180, and the oxidizer generator 120 can be configured to communicate directly with each other and/or over the network 130 via wired or wireless communication links, or a combination of the two. Each of the computing device 110, the measurement device 150, the water management system 180, and the oxidizer generator 120, can include one or more communication devices. The communication devices can include any device for communicating over a wired and/or wireless communication channel or communication link. In certain embodiments, communication devices can include one or more of the following: transceivers, transmitters, receivers, communication cards, network connectors, network adapters, and/or integrated circuits. Other types of communication devices also can be used. In certain embodiments, the computing devices 110 may represent desktop computers, laptop computers, mobile devices (e.g., smart phones, personal digital assistants, tablet devices, or any other devices that are mobile in nature), and/or other types of computing devices.

Each of the computing device 110, the measurement device 150, the water management system 180, and the oxidizer generator 120 also can be equipped with one or more computer storage devices and one or more processing devices that are capable of executing computer program instructions. The computer storage devices may be physical, non-transitory mediums in certain embodiments. The one or more storage devices can communicate with the one or more processors, and the one or more processors can execute any instructions stored on the one or more storage devices. The one or more storage devices may include: i) non-volatile memory, such as, for example, read only memory (ROM) or programmable read only memory (PROM); and/or (ii) volatile memory, such as, for example, random access memory (RAM), dynamic RAM (DRAM), static RAM (SRAM), etc. In certain embodiments, the one or more storage devices can comprise (i) non-transitory memory and/or (ii) transitory memory. The one or more processors can include one or more central processing units (CPUs), controllers, microprocessors, digital signal processors, and/or computational circuits.

Embodiments or aspects of the techniques described herein may include a computer program product accessible from a computer-usable or computer-readable medium providing program code for use by or in connection with a computer or any instruction execution system. A computer-usable or computer-readable medium may include any apparatus that stores, communicates, propagates, or transports the program for use by or in connection with the instruction execution system, apparatus, or device. The medium can be a magnetic, optical, electronic, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. The medium may include a computer-readable storage medium, such as a semiconductor or a solid state memory, a magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and an optical disk.

The measurement device 150 can be utilized to make a variety of different measurements. In certain exemplary embodiments, the measurement device 150 can use water electrolysis to measure oxidizing compounds 165 in water, such as drinking water and/or other types of water, using oxidation reduction potential (ORP) measurement techniques. In other exemplary embodiments, the measurement device 150 can use electrolysis to take pH measurements, ion concentration measurements, potentiometric measurements, and/or other measurements.

According to certain embodiments, the measurement device 150 includes at least three electrodes 140. Each of the electrodes 140 can be constructed of a noble metal, a passivated transition metal, or a glass-like carbon (also referred to as “glassy carbons” or “vitreous carbons”). In certain embodiments, the electrodes are constructed of gold, platinum, titanium, or a glass-like carbon, or of some combination thereof. The electrodes can additionally, or alternatively, be constructed of other similar metals, compounds, or other materials that do not oxidize under the conditions applied to the measurement device 150 when the measurement device is submerged in the test fluid 160. Using such construction materials avoids the risk of corrosion, which can reduce the lifetime of the measurement device 150, elute ions into the test fluid, and cause the measurement device 150 to be insensitive to the oxidizing compounds 165 being measured.

Two of the electrodes 140 can be configured on a circuit as a reference pair, and a third one of the electrodes 140 can be used as a sensor electrode. The sensor electrode may not be included on the circuit with the reference pair. When the electrodes 140 of the measurement device 150 are submerged in a test fluid 160 and a constant current is applied to the reference pair of electrodes 140, electrolysis will split the molecules of the test fluid 160, and the electrochemical potential at which electrolysis occurs can be used as a reference voltage. In embodiments in which the test fluid 160 is water, the reference pair electrolyzes the water to split the molecules into hydrogen and oxygen. For example, the reference electrodes can conduct water oxidation and/or water reduction and, therefore, evolve oxygen gas or hydrogen gas. In certain embodiments, the constant current that is applied is 10 microamperes (uA).

The electrode 140 that is used as sensor electrode can be connected to one of the electrodes 140 included in the reference pair using a high impedance resistor, an operational amplifier, and/or another component. By measuring the voltage across this connection, the voltage difference between the reference electrodes and the sensor electrode can be calculated. As oxidizing compounds 165 are added to the test fluid 160 (e.g., to sanitize the test fluid 160), the potential on the sensor electrode will increase, and the measured voltage between the reference pair and the sensor electrode will change. Because this change is relative to the concentration of the oxidizing compounds 165, the voltage measurement can be calibrated as an oxidizer concentration measurement (e.g., V_(ac) in FIG. 2) that indicates the amount of oxidizing compounds 165 in the test fluid 160.

In certain embodiments, one of the electrodes 140 included in the reference pair can measure a voltage indicating an electrochemical potential at which electrolysis occurs in the test liquid 160, and the sensor electrode can measure a voltage indicating an oxidizing potential of the test fluid 160. The measurement device 150 can then subtract the voltage measured by the sensor electrode from the voltage measured by the electrode 140 included in the reference pair to calculate the oxidizer concentration measurement.

According to certain embodiments, the measurement device 150 also can be configured to execute a self-cleaning function on the electrodes 140. During normal operation (e.g., when the measurement device 150 is operating in a potentiometric mode and is being utilized to measure and/or control levels of oxidizing compounds 165 in the test fluid 160), the surface of the electrodes 140 may be reduced, thereby causing a gain in electrons. To combat this reduction, which occurs during normal operation, the measurement device 150 also can be operated in a reverse polarization mode that executes the self-cleaning function. During use in the reverse polarization mode, the measurement device 150 utilizes an H-bridge, or other equivalent electrical component, to reverse the current that is applied to the reference pair of electrodes 140. This reversal of the current can produce a redox (or reduction-oxidation) reaction on the reference pair of electrodes 140, which is inverse to that current used during normal operation and which reverses the reduction by oxidizing the surface of the electrodes 140.

The measurement device 150 also can take measurements of the oxidizing compounds 165 when operating in the chronopotentiometric mode. In some embodiments, the measurements taken by the measurement device 150 in the chronopotentiometric mode can be used to confirm the accuracy of the measurements taken by the measurement device 150 in the normal or potentiometric mode. To deduce oxidizer concentration measurements, the measurement device 150 can short one or more of the electrodes 140 to an electrical ground, which can have the effect of applying a reducing potential to electrodes 140 and purging the surface of the electrode of oxidizing compounds 165 by a process of electrochemical reduction. The concentration of the oxidizing compounds 165 may be deduced by measuring both the maximum voltage and the time to reach that maximum voltage. As the recovery time will be shortened with increases in concentration of oxidizing compounds 165, a chronopotentiometric measurement of oxidizer concentration can be ascertained.

According to certain embodiments, the measurement device 150 can include a fourth electrode 140, which also is constructed of a noble metal, a passivated transition metal, a glass-like carbon, and/or some combination thereof. This fourth electrode 140 can be paired with the sensor electrode, thus allowing either pair of electrodes to be used as a reference pair in taking measurements and/or to implement the self-cleaning procedure. It should be noted that the fourth electrode 140 is optional, and the measurement device 150 is capable of functioning without the inclusion of the fourth electrode 140.

According to certain embodiments, the measurement device 150 can include a temperature measurement component 170 that is configured to measure or determine the temperature of the test fluid 160. The temperature measurement component 170 can include a thermistor and/or other device that is capable of measuring the temperature of the test fluid 160. The temperature readings generated by the temperature measurement component 170 can be used by the measurement device 150, along with other data (e.g., oxidizer concentration measurements) to adjust and/or control (e.g., to increase or decrease) the concentration of the oxidizing compounds 165 in the test fluid 160.

The measurement device 150 can be used to detect and/or measure oxidizing compounds 165 in various test fluids 160. In certain embodiments, the tests liquids 160 can include water, (e.g., drinking water, non-potable water, distilled water, deionized water, and/or other types of water). The tests liquids 160 can additionally, or alternatively, include alcohols (e.g., ethanol, methanol, and other alcohols) and/or electrolyze-able organic solvents (e.g., acetic acid).

In certain embodiments, the measurement device 150 can be used to detect and measure microbial life in test fluids 160 (e.g., water). For example, as aerobic microbial life consumes oxygen in order to live and propagate, a concentration of microbes in a test fluid 160 can reduce the oxidizing compounds 165. This reduction of oxidizing compounds 165 in the test fluid 160 can therefore be used to measure the microbial life content.

The measurement device 150 can be used to detect and measure various types of oxidizing compounds 165. Such oxidizing compounds 165 can include, but are not limited to, any or all of the following: oxygen (O2), ozone (O3), hydrogen peroxide (H2O2) (as well as other inorganic peroxides), fluorine (F2), chlorine (Cl2), halogen compounds, nitric acid (HNO3), nitrate compounds, sulfuric acid (H2SO4), peroxydisulfuric acid (H2S2O8), peroxymonosulfuric acid (H2SO5), chlorite, chlorate, perchlorate, hypochlorite (and other hypohalite compounds), household bleach (NaClO), hexavalent chromium compounds (e.g., chromic and dichromic acids and chromium trioxide, pyridinium chlorochromate, and chromate/dichromate compounds), permanganate compounds (e.g., potassium permanganate), sodium perborate, nitrous oxide (N2O), nitrogen dioxide (NO2), dinitrogen tetroxide (N2O4), potassium nitrate (KNO3), and/or sodium bismuthate.

In certain embodiments, the measurement device 150 also can be used to detect and measure various types of reducing compounds. Such reducing compounds can include, but are not limited to, any or all of the following: hydrogen, diborane, sodium borohydride (NaBH4), sulfur dioxide, sulfite compounds, dithionates (e.g., Na2S2O6), thiosulfates (e.g., Na2S2O3), iodides (e.g., KI), hydrazine, diisobutylaluminium hydride (DIBAL-H), oxalic acid, formic acid (HCOOH), ascorbic acid (C6H8O6), reducing sugars, phosphites, hypophosphites, phosphorous acid, dithiothreitol (DTT), carbon monoxide (CO), cyanides, carbon (C), tris-2-carboxyethylphosphine hydrochloride (TCEP), compounds containing the Fe2+ ion (e.g., such as iron(II) sulfate), and/or compounds containing the Sn2+ ion (e.g., such as tin(II) chloride).

In certain embodiments, the measurement device 150 can be incorporated into a water management system 180. The water management system 180 can include any system, device, and/or apparatus that produces, generates, stores, manages, and/or distributes drinking water and/or other types of water. For example, the measurement device 150 can be incorporated into a water management system 180 that produces or generates liquid water by extracting water vapor from ambient air or atmospheric air. In certain embodiments, the measurement device 150 and/or related techniques described herein can be utilized in connection with the systems, methods, and apparatuses described in: (i) U.S. patent application Ser. No. 15/482,104 filed on Apr. 7, 2017 (U.S. Patent Publication No. 2017-0294876) entitled “SOLAR THERMAL UNIT”; (ii) U.S. patent application Ser. No. 15/600,046 filed on May 19, 2017 (U.S. Patent Publication No. 2018-0043295) entitled “SYSTEMS AND METHODS FOR WATER EXTRACTION CONTROL”; (iii) International Patent App. No. PCT/US18/49411 filed on Sep. 4, 2018 entitled “SYSTEMS AND METHODS FOR MANAGING PRODUCTION AND DISTRIBUTION OF LIQUID WATER EXTRACTED FROM AIR”; (iv) International Patent App. No. PCT/US18/49398 filed on Sep. 4, 2018 entitled “SYSTEMS AND METHODS TO PRODUCE LIQUID WATER EXTRACTED FROM AIR”; (v) International Patent App. No. PCT/US18/42098 filed on Jul. 13, 2018 entitled “SYSTEMS FOR CONTROLLED TREATMENT OF WATER WITH OZONE AND RELATED METHODS THEREFOR”; and/or (vi) International Patent App. No. PCT/US15/61921 filed on Nov. 20, 2017 entitled “SYSTEMS AND METHODS FOR GENERATING LIQUID WATER FROM AIR.” Each of the aforementioned disclosures is herein incorporated by reference in its entirety. The measurement device 150 and/or techniques described herein can be used in connection with other types of water management systems as well.

In such water management systems or in other systems, the test fluid 160 can be water and the oxidizing compounds 165 (e.g., ozone) can be applied to water in order to sanitize the water and make it safe for consumption. The measurement device 150 described herein can be configured to measure the concentration of the oxidizing compounds 165 in the water to ensure that a sufficient amount of the oxidizing compounds 165 has been applied to sterilize the water and/or to ensure that the water is safe for drinking.

The oxidizer generator 120 can be any device or apparatus that is configured to generate and/or apply oxidizing compounds 165 to the test fluid 160. For example, in certain embodiments (e.g., such as those in which the test fluid 160 comprises water), the oxidizer generator 120 can include an ozone generator that is configured to generate and apply ozone to sterilize water or other test fluids. The oxidizer generator 120 can additionally, or alternatively, be configured to generate and/or apply other types of oxidizing compounds 165 to the test fluid, including any of the oxidizing compounds 165 mentioned in this disclosure. In certain embodiments, the measurements taken by the measurement device 150 can be used to control (e.g., to increase or decrease) the concentration of the oxidizing compounds 165 in the test fluid 160. In certain embodiments, the oxidizer generator 120 may be integrated with the water management system 180 to control the concentration of the oxidizing compounds 165 in test fluids 160 that include water.

As mentioned above, the measurement device 150 can be used in testing liquids 160 other than water and can take a variety of different measurements. For example, in certain embodiments, the electrodes 140 included in the measurement device 150 can include one or more pH electrodes and/or proton selective electrodes that enable the measurement device 150 to apply electrolysis to the test fluid 160 for taking pH measurements, acid concentration measurements, base measurements, and/or the like. Alternatively, or additionally, the electrodes 140 of the measurement device 150 can include one or more ion selective electrodes (ISE) that enable the measurement device 150 to apply electrolysis to the test fluid 160 for taking ion concentration measurements.

In certain embodiments, the measurement device 150 and/or water management system 180 implements a control function for regulating the concentration of the oxidizing compounds 165 in the test fluid 160. For example, in certain embodiments, the measurement device 150 and/or water management system 180 may regulate the concentration of ozone that is applied to disinfect or sterilize water to ensure that the water is potable and safe for consumption. The control function may be implemented using one or more processors (e.g., one or more microcontrollers) integrated into the measurement device 150 and/or water management system 180. The control function can activate the oxidizer generator 120 if the voltage indicating the oxidizer or ozone concentration measurement reaches a first specified threshold (e.g., indicating that ozone should be applied to reduce the concentration of microbial life in the water), and can deactivate the oxidizer generator 120 if the voltage indicating the oxidizer or ozone concentration measurement reaches a second specified threshold (e.g., indicating the current concentration of ozone is sufficient and/or that the water is safe for consumption).

In certain embodiments, in response to reaching the second threshold, the control function implements a timeout (e.g., 5 minutes, 10 minutes, 15 minutes, or 1 hour) during which the measurement device 150 does not take measurements and the oxidizer generator 120 does not apply oxidizing compounds 165. In certain embodiments, the control function can be configured to execute a closed loop control technique, in which the measurement device 150 will cause the oxidizer generator 120 to apply ozone to maintain a predefined ozone voltage measurement, and will cut off power to the measurement device 150 and/or oxidizer generator 120 when the voltage is registered as sufficient (e.g., when the voltage reaches the second threshold).

The computing device 110 can be configured to access the measurement device 150, the oxidizer generator 120, and/or the water management system 180 to monitor and/or control various aspects of the system 100. For example, the computing device 110 can be configured to review measurements and other data generated by the measurement device 150. The computing device 110 also can be configured to transmit commands to the measurement device 150, the oxidizer generator 120, and/or the water management system 180 for switching between potentiometric and chronopotentiometric modes, executing the self-cleaning function, managing the control functions, adjusting concentrations of oxidizing compounds 165 in the test fluid 160, and/or performing other related functions. The computing device 110 can be operated by an administrator or other individual who is associated with managing the measurement device 150 and/or water management system 180.

The embodiments described herein provide a variety of advantages over conventional measurement devices and probes. Some of the advantages include the ability to extend the lifetime of the measurement device 150 and to increase the reliability of any measurements taken using the measurement device 150. This can be attributed, at least in part, to the structure of the measurement device 150, which utilizes noble metals, passivated transition metals, and/or glassy carbons for the electrodes 140 immersed in the test fluid 160, and the electrolysis-based techniques utilized to take the measurements. Another significant advantage is the ability of the measurement device 150 to operate in a reverse polarization mode that allows the measurement device 150 to self-clean the surfaces of the electrodes 140. A further advantage of the device is the ability to operate in a chronopotentiometric mode to take measurements that can be used to confirm the measurements taken during normal operation. This technology-based solution marks an improvement over existing measurement devices and probes.

FIG. 2 is a circuit diagram of a control board 200 that may be utilized by a measurement device (e.g., measurement device 150 in FIG. 1) in accordance with certain embodiments. In certain embodiments, the control board 200 may be utilized for a measurement device that is assessing water and applying ozone as an oxidizing compound to sterilize the water.

The control board 200 includes, inter alia, the following components: a microcontroller 210, a power supply 220, an H-bridge 230, a MOSFET (metal-oxide-semiconductor field-effect transistor) 240, a pair of resistors 250, and an operational amplifier (op amp) 260. In this exemplary embodiment, the power supply 220 can be a 10 uA constant current supply, the MOSFET 240 can be an N-channel MOSFET, the op amp 260 can be a differential op amp, and the resistors 250 can be 30 megaohms (Mohms) resistors. In other embodiments, different types of components can be integrated into the control board 200 based on the test fluid and/or based on the types of measurements that are being deduced.

The control board 200 also includes three electrical connections—A, B, and C—for each of three connected electrodes (e.g., electrodes 140 in FIG. 1). For example, in certain embodiments, the three electrical connections—A, B, and C—may be connected to wires, and the electrodes can be attached to the end of the wires and suspended in the test fluid. In this example, the electrodes corresponding to electrical connections A and B form the reference pair, and the electrical connection C corresponds to the sensor electrode. As explained above, in other embodiments, the measurement device may include a fourth electrode as well. In such embodiments, an additional electrical connection can be added to the control board 200 to facilitate connection of the fourth electrode. The fourth node can be included on a circuit with the electrical connection C corresponding to the sensor electrode. T1 and T2 are electrical connections to a temperature measurement component (e.g., temperature measurement component 170 in FIG. 1).

The power supply 220 may be configured to regulate a fixed current by adjusting the output voltage as the load changes. A constant current power supply provides a regulated 1 or 10 pA of current ranging from 0 to 3 VDC (volts DC). The constant current supply may be implemented using an instrumentation operational amplifier. When the current is applied to electrodes A and B, the water or test fluid will be electrolyzed, and this circuit will be used to produce V_(ab), which is a measure of the test fluid conductivity, and Ref, which is a measure of the electrochemical potential at which electrolysis occurs in the test fluid. Under ideal conditions, water electrolysis occurs at ˜1.23 V (volts). However, Ref reflects the true voltage for performing electrolysis and, thus, can vary based on actual operating conditions (e.g., based on the separation distance of the electrodes). Electrode C measures a voltage indicating an oxidizing potential of the test fluid, which is shown as V_(0p). Ref and V_(0p) are passed through the resistors 250 and supplied to op amp 260. Op amp 260 subtracts V_(0p) from Ref to produce V_(ac), which serves as an indicator of the oxidation potential voltage. T1 is the electrical connection to the temperature measurement component and T2 is a connection to a ground associated with the temperature measurement component. Temp is a voltage indicating the temperature of the test fluid.

The microcontroller 210 receives the following inputs:

(1) V_(ab): this is the water electrolysis cell voltage (Vab=A−B) and serves as an indicator of test fluid conductivity;

(2) V_(ac): this is the oxidizer concentration measurement (in this case, an ozone concentration measurement) and serves as an indicator of the oxidation potential voltage (Vac=A−C);

(3) Temp: this is a temperature measurement of the test fluid 160 received from the temperature measurement component (e.g., thermistor);

(4) 3.3 V: this is the power supplied to the control board 200; and

(5) SDA/SCL: these are I²C network signals between the microcontroller 210 and a host controller.

The outputs of the microcontroller 210 include:

(1) H-Bridge output signal: this output controls the current flow and instructs the H-Bridge whether the current should be reversed (e.g., depending upon whether not the device is operating in the normal mode or the reverse polarization mode);

(2) MOSFET output signal: this output controls whether or not electrode C is connected to a ground by sending instructions to the MOSFET; and

(3) SDA/SCL output signals: these outputs are provided as part of an I²C network and can communicate the electrode voltage measurements (V_(ab) and V_(ac)) as well as the temperature measurement (T1) upon request from the host controller.

The microcontroller 210 can use the electrode voltage measurements (V_(ab) and V_(ac)) as well as the temperature measurement (T1) to implement the control function for increasing and/or decreasing the concentration of ozone in the water. The microcontroller 210 can compare these parameters to a library of pre-stored conditions to activate and/or deactivate an ozone generation system. The library may be use the temp measurement, inter alia, to control the current that is applied to the test fluid and/or to control the oxidizing compounds that are applied to the test fluid.

As mentioned above, the measurement device can operate in a potentiometric mode (e.g., during normal operation when the concentration of the ozone or other oxidizing compound is being measured), a chronopotentiometric mode (e.g., during an operation that cleans the sensor electrode and/or takes confirmatory measurements), and a reverse polarity mode (e.g., during a self-cleaning operation that cleans the electrodes and/or takes confirmatory measurements). When operating in the potentiometric mode, the H-Bridge output signal provided by the microcontroller 210 can instruct the H-Bridge 230 that the current flow is not to be reversed, and the MOSFET output signal can instruct MOSFET 240 that the electrode 140 corresponding to electrical connection C is not to be connected to a ground. When operating in reverse polarity mode, the H-Bridge output signal provided by the microcontroller 210 can instruct the H-Bridge 230 that the current flow is to be reversed. When operating in chronopotentiometric mode the MOSFET output signal can instruct MOSFET 240 that the electrode corresponding to electrical connection C is to be connected to a ground. Connecting to the ground will close the circuit between electrode C and the ground, and will result in a “purge” that is intended to reduce any residual oxidizer on the surface of the electrode.

The SDA/SCL connections connect the microcontroller 210 to a host controller. In certain embodiments, the microcontroller 210 acts as a “slave” device and communicates the electrode voltage measurements and temperature measurements upon request from the host controller. The microcontroller 210 also can receive commands from the host controller for controlling the H-bridge 230 for electrodes A and B, and the MOSFET 240 (e.g., which may be an N-channel MOSFET) for electrode C.

FIG. 3 is a diagram 300 illustrating how measurements are computed in accordance with certain embodiments. This diagram illustrates how measurements may be computed by the measurement device (e.g., measurement device 150 in FIG. 1) for various embodiments in which ozone concentration is being measured in water.

The axis on the left represents a range of possible voltages associated with the electrochemical potential at which the process of water electrolysis occurs. This axis is not labeled because the values may be dependent on the type of electrodes that are used. The bracket labeled “Water Electrolysis Voltage 1.23V” represents the voltage to perform water electrolysis under standard conditions. On the far right side, there is a bracket labeled “Cell voltage” that represents the measurement of voltage used to conduct water electrolysis, which considers all features of the true voltage measurement (e.g., such as the area of the test fluid 160 and the distance or separation of the electrodes).

The “Over potentials” for the reference electrodes represent the difference between the cell voltage and the standard water electrolysis voltage. The electrochemical reactions for water electrolysis also are listed in the figure. An ozone voltage is a function of ozone concentration and can be any value in a range that falls within the water electrolysis reaction voltages. The difference between this voltage and the voltage of the reference is reported as the oxidation potential measurement. In certain embodiments, the reference electrodes are conducting water oxidation and, therefore, are evolving oxygen gas. The reference electrodes can additionally, or alternatively, conduct water reduction and, therefore, evolve hydrogen gas.

Turning ahead in the drawings, FIGS. 4-6 illustrate flow charts for exemplary methods 400, 500, 600, respectively, according to certain embodiments. Methods 400, 500, 600 are merely exemplary and are not limited to the embodiments presented herein. Methods 400, 500, 600 can be employed in many different embodiments or examples not specifically depicted or described herein. In some embodiments, the activities of methods 400, 500, 600 can be performed in the order presented. In other embodiments, the activities of methods 400, 500, 600 can be performed in any suitable order. In still other embodiments, one or more of the activities of methods 400, 500, 600 can be combined or skipped. In many embodiments, system 100 (FIG. 1) and/or measurement device 150 (FIG. 1) can be suitable to perform methods 400, 500, 600 and/or one or more of the activities of methods 400, 500, 600. In these or other embodiments, one or more of the activities of methods 400, 500, 600 can be implemented as one or more computer instructions configured to run at one or more processors and configured to be stored at one or more non-transitory storage devices. Such non-transitory memory storage devices can be part of system 100 (FIG. 1), measurement device 150 (FIG. 1) and/or control board 200 (FIG. 2). The processor(s) can be similar or identical to the processor(s) described above with respect to system 100 (FIG. 1).

FIG. 4 is a flow chart of an exemplary method 400 in accordance with certain embodiments. Method 400 can comprise an activity 410 of applying a constant current to a test fluid including an oxidizing compound. Method 400 can further comprise an activity 420 of measuring a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid. Method 400 can further comprise an activity 430 of measuring a second voltage indicating an oxidizing potential of the test fluid. Method 400 can further comprise an activity 440 of calculating an oxidizer concentration measurement indicating the concentration of the oxidizing compound in the test fluid based on a voltage difference between the reference voltage and the second voltage. As an example, one of or both of system 100 in FIG. 1 and control board 200 in FIG. 2 can be used to perform some or all of one or more of activities 410, 420, 430, and 440.

FIG. 5 is a flow chart of a second exemplary method 500 in accordance with certain embodiments. Method 500 can comprise an activity 510 of submerging electrodes, including at least a pair of reference electrodes and a sensor electrode in a test fluid that includes oxidizing compounds. Method 500 can further comprise an activity 520 of applying a constant current to the pair of reference electrodes submerged in the test fluid. Method 500 can further comprise an activity 530 of measuring a conductivity or electrical resistance of the test fluid based on the constant current using the sensor electrode. Method 500 can further comprise an activity 540 of measuring an oxidation potential voltage of the test fluid using the pair of reference electrodes. Method 500 can further comprise an activity 550 of measuring a temperature of the test fluid using a temperature measurement component. Method 500 can further comprise an activity 560 of using the measurements to control an oxidizer generation system that is able to apply oxidizing compounds to the test fluid. As an example, one of or both of system 100 in FIG. 1 and control board 200 in FIG. 2 can be used to perform some or all of one or more of activities 510, 520, 530, and 540.

FIG. 6 is a flow chart of a third exemplary method 600 in accordance with certain embodiments. Method 600 can comprise an activity 610 of submerging electrodes, including at least a pair of reference electrodes and a sensor electrode in a test fluid that comprises water and ozone. Method 600 can further comprise an activity 620 of applying a constant current to the pair of reference electrodes submerged in the test fluid. Method 600 can further comprise an activity 630 of measuring, using the sensor electrode, a conductivity or electrical resistance of the test fluid based on the constant current. Method 600 can further comprise an activity 640 of measuring, using the pair of reference electrodes, an ozone oxidation potential voltage. Method 600 can further comprise an activity 650 of measuring, using a temperature measurement component, a temperature of the test fluid. Method 600 can further comprise an activity 660 of utilizing the measurements to control an ozone generation system that is able to apply ozone to the test fluid. As an example, one of or both of system 100 in FIG. 1 and control board 200 in FIG. 2 can be used to perform some or all of one or more of activities 610, 620, 630, 640, 650, and 660.

Although systems and methods have been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes may be made without departing from the spirit or scope of the disclosure. Accordingly, the disclosure of embodiments is intended to be illustrative of the scope of the disclosure and is not intended to be limiting. It is intended that the scope of the disclosure shall be limited only to the extent required by the appended claims. For example, to one of ordinary skill in the art, it will be readily apparent that any element of FIGS. 1-6 may be modified, and that the foregoing discussion of certain of these embodiments does not necessarily represent a complete description of all possible embodiments. For example, one or more of the procedures, processes, and/or activities of FIGS. 4-6 may include different procedures, processes, and/or activities and be performed by many different modules and/or components, in many different orders.

All elements claimed in any particular claim are essential to the embodiment claimed in that particular claim. Consequently, replacement of one or more claimed elements constitutes reconstruction and not repair. Additionally, benefits, other advantages, and solutions to problems have been described with regard to specific embodiments. The benefits, advantages, solutions to problems, and any element or elements that may cause any benefit, advantage, and/or solution to occur or become more pronounced, however, are not to be construed as critical, required, or essential features or elements of any or all of the claims, unless such benefits, advantages, solutions, and/or elements are stated in such claim.

Moreover, embodiments and limitations disclosed herein are not dedicated to the public under the doctrine of dedication if the embodiments and/or limitations: (1) are not expressly claimed in the claims; and (2) are, or potentially are, equivalents of express elements and/or limitations in the claims under the doctrine of equivalents. 

What is claimed is:
 1. A system comprising: a test fluid comprising a concentration of an oxidizing compound; and a measurement device configured to: apply a constant current to the test fluid; measure a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid; measure a second voltage indicating an oxidizing potential of the test fluid; and calculate an oxidizer concentration measurement indicating the concentration of the oxidizing compound in the test fluid based on a voltage difference between the reference voltage and the second voltage.
 2. The system of claim 1, wherein: the test fluid is water; the oxidizing compound is ozone; the reference voltage indicates the electrochemical potential at which water electrolysis occurs in the water; and the oxidizer concentration measurement is an ozone concentration measurement.
 3. The system of claim 1, wherein the measurement device is further configured to calculate a ph measurement in the test fluid.
 4. The system of claim 1, wherein the measurement device is further configured to calculate an ion concentration measurement in the test fluid.
 5. The system of claim 1, wherein the measurement device comprises: a processor; a power supply that is configured to provide the constant current; and a first electrode, a second electrode, and a third electrode, wherein: the first electrode and the second electrode are included on a circuit to which the constant current is applied when the first electrode and the second electrode are submerged in the test fluid, and the third electrode is not included on the circuit; the first electrode is configured to measure the reference voltage; the third electrode is configured to measure the second voltage; and the first electrode, the second electrode, and the third electrode are each comprised of a noble metal, a passivated transition metal, a glass-like carbon, or some combination thereof.
 6. The system of claim 5, wherein the measurement device further comprises a fourth electrode that is paired on a second circuit with the third electrode.
 7. The system of claim 5, wherein the measurement device is configured to operate in a reverse polarization mode during which the constant current applied to the test fluid is reversed to produce a redox reaction on the first electrode and the second electrode in the test fluid.
 8. The system of claim 7, wherein, during operation in the chronopotentiometric mode, the measurement device is configured to take a second oxidizer concentration measurement of the test fluid to evaluate an accuracy of the oxidizer concentration measurement in the test fluid.
 9. The system of claim 5, wherein the measurement device further comprises a temperature measurement component that is configured to measure a third voltage indicating a temperature of the test fluid.
 10. The system of claim 9, wherein: the system further comprises an oxidizer generator that is configured to apply the oxidizing compound to the test fluid; the processor receives the reference voltage, the second voltage, and the third voltage; and the processor controls the oxidizer generator based on the reference voltage, the second voltage, and the third voltage.
 11. A method comprising: applying a constant current to a test fluid comprising a concentration of an oxidizing compound; measuring, with a measurement device, a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid; measuring, with the measurement device, a second voltage indicating an oxidizing potential of the test fluid; and calculating, with the measurement device, an oxidizer concentration measurement indicating the concentration of the oxidizing compound in the test fluid based on a voltage difference between the reference voltage and the second voltage.
 12. The method of claim 11, wherein: the test fluid is water; the oxidizing compound is ozone; the reference voltage indicates the electrochemical potential at which water electrolysis occurs in the water; and the oxidizer concentration measurement is an ozone concentration measurement.
 13. The method of claim 11, wherein the measurement device is further configured to calculate a ph measurement in the test fluid.
 14. The method of claim 11, wherein the measurement device is further configured to calculate an ion concentration measurement in the test fluid.
 15. The method of claim 11, wherein the measurement device comprises: a processor; a power supply that is configured to provide the constant current; and a first electrode, a second electrode, and a third electrode, wherein: the first electrode and the second electrode are included on a circuit to which the constant current is applied when the first electrode and the second electrode are submerged in the test fluid, and the third electrode is not included on the circuit; the first electrode is configured to measure the reference voltage; the third electrode is configured to measure the second voltage; and the first electrode, the second electrode, and the third electrode are each comprised of a noble metal, a passivated transition metal, a glass-like carbon, or some combination thereof.
 16. The method of claim 15, wherein the measurement device further comprises a fourth electrode that is paired on a second circuit with the third electrode.
 17. The method of claim 15, wherein the measurement device is configured to operate in a reverse polarization mode during which the constant current applied to the test fluid is reversed to produce a redox reaction on the first electrode and the second electrode in the test fluid.
 18. The method of claim 17, wherein, during operation in the chronopotentiometric mode, the measurement device is configured to take a second oxidizer concentration measurement of the test fluid to evaluate an accuracy of the oxidizer concentration measurement in the test fluid.
 19. The method of claim 15, wherein the measurement device further comprises: measuring a third voltage indicating a temperature of the test fluid using temperature measurement component; receiving the reference voltage, the second voltage, and the third voltage at the processor; and controlling an oxidizer generator based on the reference voltage, the second voltage, and the third voltage.
 20. A system comprising: a test fluid comprising a concentration of an oxidizing compound; and a measurement device comprising: a processor; a power supply that is configured to provide a constant current; and a first electrode, a second electrode, and a third electrode, wherein: the first electrode and the second electrode are included on a circuit to which the constant current is applied when the first electrode and the second electrode are submerged in the test fluid, and the third electrode is not included on the circuit; the first electrode, the second electrode, and the third electrode are each comprised of a noble metal, a passivated transition metal, a glass-like carbon, or some combination thereof; the first electrode is configured to measure a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid; the third electrode is configured to measure a second voltage indicating an oxidizing potential of the test fluid; and the measurement device calculates an oxidizer concentration measurement indicating the concentration of the oxidizing compound in the test fluid based on a voltage difference between the reference voltage and the second voltage.
 21. A system comprising: a test fluid; and a measurement device configured to: apply a constant current to the test fluid; measure a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid; measure a second voltage indicating a potential of the test fluid related to one of an oxidizing potential, a pH potential, or an ion concentration chemical potential; and calculate a concentration measurement in the test fluid based on a voltage difference between the reference voltage and the second voltage. 